[Mikey Likes It]

Hello I'm a dad in the process of helping my son with his Xterra. This will be my first experience with the 2005 4.0 engine but my mechanical skills are good. It appears we have a loss of compression in #3 cylinder so I may be asking a lot of question in the near future. Next step is to pull the valve cover to see if any problems are visual and check the valve lash.
Thanks for the opportunity to join and learn something new.

 

[MeToo]

You may want to do 2 compression checks of #3. The first would be dry, or just a normal check. The second would be to squirt some oil into the cylinder and then check it. If it rises a lot, then it's rings (or something else that the oil is acting to seal temporarily). If it doesn't, then pull the valve cover to see if #3 valves move.

 

[Mikey Likes It]

Good info, I forgot about the oil trick. I pulled the valve cover and the cam train looks fine. Did a quick check and both exhaust valves the same adjustment, the intake valves have a .1mm difference between them and I feel that is not an issue so the valves may be okay. checked the cylinder with a scope and looks good. When I get home today I will try oil in the cylinder. Thank you for the response.